JP2019106657A - hearing aid - Google Patents

Abstract

To provide a hearing aid capable of easily suppressing howling.SOLUTION: The hearing aid comprises: dividing means for dividing an input signal into a low frequency component and a high frequency component; full-wave rectifying means for full-wave rectification of a high frequency component signal; and synthesizing means for synthesizing the low frequency component signal and the high frequency band component signal having been subjected to the full-wave rectification.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hearing aid.

  Howling is a phenomenon in which the output sound from the earphone is fed back to the microphone and oscillates.

Patent Document 1 discloses a hearing aid whose howling is suppressed.
The hearing aid of Patent Document 1 detects the occurrence of howling and its frequency. The frequencies are phase-shifted and added according to the detected howling frequency. This attenuates the signal component of the howling frequency.

JP-A-6-22397

  The hearing aid of Patent Document 1 requires a howling frequency detection circuit (howling detection circuit). However, it is very difficult to exactly detect the occurrence of howling. The configuration of the howling detection circuit is complicated. Miniaturization of the hearing aid is required. The component parts are required to be minimized. Therefore, it is not desirable to have a complex howling detection circuit. Furthermore, it is not preferable that the amount of power consumption increases.

  The problem to be solved by the present invention is to provide a hearing aid in which howling suppression can be easily implemented.

The present invention
We propose a hearing aid with dual-wave rectification means for dual-wave rectification of the signal at the frequency at which howling occurs.

The present invention
Division means for dividing an input signal into low frequency components and high frequency components;
A double wave rectification means for double wave rectification of the signal of the high frequency range component;
A hearing aid is proposed which comprises combining means for combining the signal of the low frequency range component and the signal of the high frequency range component subjected to the double wave rectification.

The present invention is the above-mentioned hearing aid, wherein
The dividing means is
A low pass filter for passing low frequency components and a high pass filter for passing high frequency components;
The two wave rectification means is
Double-rectify the output signal from the high pass filter,
The combining means is
A hearing aid is proposed which combines the output signal from the low pass filter and the output signal from the two wave rectification means.

The present invention is the above-mentioned hearing aid, wherein
The high frequency range component includes a first high frequency range component and an Nth (N is an integer of 2 or more) high frequency range component,
The dividing means is
A band pass filter for passing the first high frequency component and a band removal filter for removing the first high frequency component;
The two wave rectification means is
Both-wave rectify the output signal from the band pass filter,
The combining means is
A hearing aid is proposed which combines the output signal from the debanding filter and the output signal from the double wave rectifying means.

The present invention is the above-mentioned hearing aid, wherein
The hearing aid in which the two-wave rectification means is a two-wave rectification circuit is proposed.

The present invention is the above-mentioned hearing aid, wherein
A hearing aid is proposed in which the high frequency band in which both waves are rectified is set based on the resonance frequency caused by the hearing aid.

The present invention is the above-mentioned hearing aid, wherein
The present invention proposes a hearing aid in which the high-frequency region subjected to both-wave rectification is set so as not to include the frequency of the maximum peak value in the amplitude spectrum of the vowel.

The present invention is the above-mentioned hearing aid, wherein
The present invention proposes a hearing aid that is set so that the frequency of the both-wave rectified high frequency region does not include the frequency of the maximum peak value and the second largest peak value in the amplitude spectrum of the vowel.

The present invention is the above-mentioned hearing aid, wherein
The high frequency band in which both waves are rectified is a hearing aid in a band of 3 kHz or more.

The present invention is the above-mentioned hearing aid, wherein
The above-mentioned high frequency band in which both waves are rectified is a hearing aid in a band of 2 kHz or more.

The present invention is the above-mentioned hearing aid, wherein
The high frequency band in which both waves are rectified is a hearing aid in a band of 1.5 kHz or more.

The present invention is the above-mentioned hearing aid, wherein
The high frequency band in which both waves are rectified is in the band of 1 kHz or more.

The present invention is the above-mentioned hearing aid, wherein
The high frequency band in which both waves are rectified is a hearing aid in a band of 8 kHz or less.

The present invention is the above-mentioned hearing aid, wherein
The high frequency band in which both waves are rectified is a hearing aid in a band of 4 kHz or less.

  Howling was easily suppressed.

Configuration diagram of the hearing aid according to the embodiment of the present invention The figure which shows the input waveform A of the both-waves rectifier circuit 14, and the output waveform B The figure which shows the specific example of the both-waves rectifier circuit 14 A diagram showing a specific example of the two-wave rectifier circuit 14 The block diagram of the hearing aid concerning the 2nd embodiment of the present invention The figure which shows the frequency characteristic of low pass filter 21 and high pass filter 22 The block diagram of the hearing aid concerning the 3rd embodiment of the present invention The figure which shows the frequency characteristic of the band pass filter 31 and the band removal filter 32. A diagram showing a pulse waveform A of a consonant input to the two-wave rectifier circuit 14 and a pulse waveform B of a consonant output from the two-wave rectifier circuit 14 Diagram showing how the seeding signal of howling returns and grows and how the seeding signal of howling rectifies and reduces Amplitude spectrum of vowel "A" Amplitude spectrum of vowel "i" Amplitude spectrum of vowel "u" Amplitude spectrum of vowel "e" Amplitude spectrum of vowel "o" A diagram showing the waveform of a 1 kHz signal S1 A diagram showing the result of Fourier transform of the signal S1 A diagram showing a waveform of a signal S2 obtained by half-wave rectifying the signal S1 A diagram showing the result of Fourier transform of the signal S2

  The present invention is a hearing aid. The hearing aid comprises a double wave rectifying means. The two-wave rectification means performs two-wave rectification on a signal at a frequency at which howling occurs. The two-wave rectification means is, for example, a two-wave rectification circuit. The two-wave rectification means (two-wave rectification circuit) performs, for example, two-wave rectification on a signal of a high frequency range component. The component subjected to double-wave rectification is, for example, in a band of 1 kHz or more. For example, it is in a band of 1.5 kHz or more. For example, it is in a band of 2 kHz or more. For example, it is in a band of 3 kHz or more. For example, it is in a band of 8 kHz or less. For example, it is in a band of 5 kHz or less. For example, it is in a band of 4 kHz or less. It may not be rectified over an unnecessarily wide range. Only the minimum necessary frequency components may be rectified. In extreme terms, only the frequency component where howling occurs may be rectified. Howling can also occur at frequencies specific to hearing aids. In this case, only specific frequency components may be rectified. Said hearing aid preferably comprises splitting means. The dividing means divides an input signal into two or more components. The division may be two or three or more. For example, it is divided into low frequency components and high frequency components. The low frequency range component includes, for example, the frequency of the maximum peak value (preferably, the maximum peak value and the second largest peak value) in the amplitude spectrum of the vowel. For example, 2 kHz or less. For example, 1.5 kHz or less. For example, 1 kHz or less. The low frequency components are not double wave rectified. The hearing aid preferably comprises synthesis means. The combining means combines the signal of the component that has not been rectified and the signal of the component that has been double-wave rectified.

The dividing means is composed of, for example, a low pass filter and a high pass filter. The low pass filter passes low frequency components. The high pass filter passes high frequency components.
The dividing means is composed of, for example, a band pass filter and a band elimination filter. The band pass filter passes a signal of a frequency (for example, a frequency of the high frequency region or a frequency at which howling occurs) rectified by the two-wave rectifier (two-wave rectifier circuit). The band removal filter removes the passing signal. In a sense, the high pass filter can be considered to be a band pass filter. The low pass filter can be considered to be a band elimination filter.
Hereinafter, specific embodiments will be described and described.

First Embodiment
FIG. 1 is a block diagram of a hearing aid according to a first embodiment of the present invention.
The hearing aid H includes a microphone 11, an amplifier 12, a dividing unit 13, a double wave rectifying circuit 14, a synthesizing unit 16, and an earphone (speaker) 17.

  The microphone 11 converts voice into an electrical signal.

  The amplifier 12 amplifies the output signal from the microphone 11.

  The dividing unit 13 divides the output signal from the amplifier 12 into a low frequency component and a high frequency component.

  The two-wave rectification circuit 14 performs two-wave rectification on the signal of the divided high frequency region component. The two-wave rectifier circuit 14 is also called a full-wave rectifier circuit. The two-wave rectifier circuit 14 is also called an absolute value circuit.

  FIG. 2 is an explanatory diagram of an input waveform A and an output waveform B of the both-wave rectifier circuit 14.

  3 and 4 show specific examples of the both-wave rectifier circuit 14. FIG.

  The two-wave rectifier circuit 14 includes a phase inverter 5, diodes 6A and 6B, and an adder 7 (see FIG. 3). An input signal (high frequency range component) from the dividing unit 13 is input (branched) to the diode 6A and the phase inverter 5. The diode 6A rectifies the input signal. The phase inverter 5 inverts the phase of the input signal. The diode 6 B rectifies the signal phase-reversed by the phase inverter 5. The adder 7 adds up the signal rectified by the diode 6A and the signal rectified by the diode 6B.

  The two-wave rectifier circuit 14 includes a transformer 8, diodes 6A and 6B, and an adder 7 (see FIG. 4). An input signal (high frequency range component) from the dividing unit 13 is added to a transformer 8 having a center tap. The diode 6A and the diode 6B rectify the output signal from the transformer 8. The adder 7 adds up the signal rectified by the diode 6A and the signal rectified by the diode 6B.

  The two-wave rectifier circuit 14 is not limited to the above example (FIGS. 3 and 4). For example, without using a diode, a two-wave rectification circuit using the rectification characteristic of the element may be used. It is also possible to use a double-wave rectifier circuit that rectifies using a single power supply operational amplifier or an RR (rail-to-rail) operational amplifier.

  The output signal of the two-wave rectifier circuit 14 does not include the fundamental wave component of the input signal. The fundamental wave component disappears. Thus, for example, the output signal for an input signal with a frequency of 1 kHz has frequency components other than 1 kHz.

  The synthesis unit 16 synthesizes the divided low frequency component signal and the double wave rectified high frequency component signal.

  The earphone 17 converts the signal combined by the combining unit 16 into voice and outputs the voice.

Second Embodiment
FIG. 5 is a block diagram of a hearing aid according to a second embodiment of the present invention.
The present embodiment is an example in which the dividing unit 13 includes a low pass filter 21 and a high pass filter 22.

  The low pass filter 21 passes low frequency components (for example, 1 kHz or less) of the output signal from the amplifier 12.

  The high pass filter 22 passes high frequency components (for example, 1 kHz or more) of the output signal from the amplifier 12.

  The cutoff frequency set for the low pass filter 21 and the high pass filter 22 is preferably, for example, 1 kHz.

  The two-wave rectification circuit 14 performs two-wave rectification on the high frequency component signal that has passed through the high pass filter 22. The signal that has passed through the low pass filter 21 is not rectified.

  The combining unit 16 combines the output signal from the low pass filter 21 and the output signal from the both-wave rectifier circuit 14.

  FIG. 6 is a diagram showing frequency characteristics of the low pass filter 21 and the high pass filter 22. As shown in FIG. The characteristic of the low pass filter 21 is indicated by reference numeral 23. The characteristic of the high pass filter 22 is indicated by reference numeral 24.

Third Embodiment
FIG. 7 is a block diagram of a hearing aid according to a third embodiment of the present invention.
The present embodiment is an example in which the dividing unit 13 is configured of a band pass filter 31 and a band removing filter 32. In the present embodiment, the high frequency range is divided into a first high frequency range and a second high frequency range. The second high frequency range is higher than the first high frequency range. Although this example is described as an example of two divisions, it may be three divisions.

  The band pass filter 31 passes the component of the first high frequency range of the output signal from the amplifier 12.

  The band removal filter 32 removes the component of the first high frequency range of the output signal from the amplifier 12. The band elimination filter 32 passes the low frequency component and the second high frequency component.

  The pass band of the band pass filter 31 and the removal band of the band removal filter 32 are, for example, 3 to 5 kHz. Or it is 2 kHz or more. Or it is 1 kHz or more. It is 4.5 kHz or less. It may be 1 to 8 kHz. Of course, it is not limited to this. For example, a frequency at which howling tends to occur can be predicted and set.

  The two-wave rectification circuit 14 performs two-wave rectification on the component of the first high frequency region that has passed through the band pass filter 31. The signal passed through the band elimination filter 32 is not double-wave rectified.

  The synthesis unit 16 synthesizes the output signal from the band removal filter 32 and the output signal from the both-wave rectification circuit 14.

  FIG. 8 is a diagram showing the frequency characteristics of the band pass filter 31 and the band removal filter 32. As shown in FIG. The characteristic of the band pass filter 31 is indicated by reference numeral 34. The characteristic of the debanding filter 32 is shown at 33.

  When the howling occurrence frequency is determined (for example, in the case of howling by single-frequency earphone resonance), the third embodiment (provided with the band pass filter 31 and the band removal filter 32) is suitable. If the howling frequency changes instably (for example, howling is caused by earphone resonance present at a plurality of frequencies), the second embodiment (including the low pass filter 21 and the high pass filter) is suitable.

In the present invention, the two-wave rectifier circuit 14 is operated in a high frequency range (for example, 1 kHz or more).
The vowel has an important component for recognizing the sound in a low frequency range (for example, 1 kHz or less) (see FIGS. 11 to 15). The vowel is a positive / negative asymmetric signal having periodicity. If this waveform is distorted, the listener may feel uncomfortable. In the present invention, the two-wave rectifier circuit 14 is not operated in the low frequency band where the important component of the vowel component is included. For this reason, the clarity of vowels is maintained. On the other hand, the important component of the consonant is in the high frequency range. Hearing appears to be insensitive to distortion at high frequencies. Therefore, even if distortion occurs in the high frequency region, it does not seem to cause a major problem.

  The two-wave rectifier circuit 14 increases the pulse frequency of the high frequency component of the input signal. FIG. 9 shows a pulse waveform A of a consonant input to the both-wave rectifier circuit 14 and a pulse waveform B of a consonant output from the both-wave rectifier circuit 14. Consonants are non-periodic sounds including rubs and plosives. By passing through the both-wave rectifier circuit 14, the waveform of the consonant becomes a pulse waveform having twice the frequency. Consonants retain their function even if their frequency is doubled.

  The two-wave rectifier circuit rectifies all the positive and negative of the signal to positive (or negative). Howling is a phenomenon in which positive and negative symmetrical waveforms that become seeds grow. Therefore, the two-wave rectifier circuit 14 effectively acts on the howling waveform.

If the present invention is not used, the howling seed signal will return and grow. This situation is shown in FIG. 10A.
When the present invention (two-wave rectifier circuit 14) is adopted, the howling seed signal is rectified to have a positive only (or only negative) waveform. In this case, the howling seed signal does not grow because the original frequency component (fundamental wave) disappears. Howling is suppressed. This situation is shown in FIG. 10B.

Phase inversion or inversion cancellation has been proposed as a howling elimination method. However, in these methods, it is necessary to detect the occurrence of howling. However, it is very difficult to exactly detect the occurrence of howling. Even if the phase is reversed, another howling occurs. The phase inversion scheme is not a definitive solution. In the scheme of adding signals in antiphase, all signals are canceled out. Therefore, the signal of the consonant is also erased. Furthermore, when the signal of howling disappears, new howling occurs, so that permanent howling can not be prevented.
The present invention does not eliminate consonants. There is no new howling. Does not require howling detection.
The invention can also be practiced with digital systems. The two-wave rectifier circuit may digitally rectify the input signal. In this case, it is preferable to include a delay unit for delaying the low frequency component signal divided by the dividing unit 13. The delay unit absorbs the time delay due to the processing of the both-wave rectifier circuit 14.

The rectifier circuit includes a half wave rectifier circuit and a double wave rectifier circuit. In the above embodiment, a double wave rectification circuit is adopted, and a half wave rectification circuit is not adopted. Even if a half wave rectification circuit is adopted, the effect of the present invention is not exerted. The reason is as follows.
FIG. 16 shows the waveform of the 1 kHz signal S1. FIG. 17 shows the result of Fourier transform of the signal S1 (see FIG. 16). According to the result of Fourier transform (see FIG. 17), the 1 kHz component of the signal S1 is 1 v.
FIG. 18 shows a waveform of a signal S2 obtained by half-wave rectifying the 1 kHz signal S1. FIG. 19 shows the result of Fourier transform of the signal S2 (see FIG. 18). According to the result of Fourier transform (see FIG. 19), the 1 kHz component of the signal S2 is 500 mv.
That is, in the half wave rectification circuit, the fundamental wave of the input signal remains. For this reason, even if a half wave rectification circuit is adopted, there is no howling preventing effect.

  The invention is also applicable to acoustic devices similar to hearing aids. Application is possible to a mobile phone, a megaphone, etc.

  The present invention has been described above with reference to the preferred embodiments. The present invention is not necessarily limited to the above embodiment. Various modifications and implementations can be made within the scope of the technical idea of the present invention.

H Hearing aid 5 Phase inverter 6A, 6B Diode 7 Adder 8 Transformer 11 Microphone 12 Amplifier 13 Divider 14 Full-wave rectifier 16 Synthesizer 17 Earphone 21 Low-pass filter 22 High-pass filter 23 Low-pass filter characteristic 24 High-pass filter characteristic 31 Band pass filter 32 band rejection filter 33 band rejection filter characteristic 34 band pass filter characteristic

Claims (13)

A hearing aid comprising two-wave rectification means for two-wave rectification of a signal at a frequency at which howling occurs. Division means for dividing an input signal into low frequency components and high frequency components;
A double wave rectification means for double wave rectification of the signal of the high frequency range component;
A hearing aid comprising: combining means for combining the low frequency component signal and the double wave rectified high frequency component signal. The dividing means is
A low pass filter for passing low frequency components and a high pass filter for passing high frequency components;
The two wave rectification means is
Double-rectify the output signal from the high pass filter,
The combining means is
The hearing aid according to claim 2, wherein the output signal from the low pass filter and the output signal from the two-wave rectification means are combined. The high frequency range component includes a first high frequency range component and an Nth (N is an integer of 2 or more) high frequency range component,
The dividing means is
A band pass filter for passing the first high frequency component and a band removal filter for removing the first high frequency component;
The two wave rectification means is
Both-wave rectify the output signal from the band pass filter,
The combining means is
3. The hearing aid according to claim 2, wherein the output signal from the debanding filter and the output signal from the two-wave rectifying means are combined. The hearing aid according to any one of claims 1 to 4, wherein the two-wave rectification means is a two-wave rectification circuit. The hearing aid according to any one of claims 1 to 5, wherein the high frequency band in which both waves are rectified is set based on a resonance frequency caused by the hearing aid. The hearing aid according to any one of claims 1 to 6, wherein the high-frequency region subjected to both-wave rectification is set so as not to include the frequency of the maximum peak value in the amplitude spectrum of the vowel. The hearing aid according to any one of claims 1 to 6, wherein the high-frequency region subjected to both-wave rectification is set so as not to include the frequency of the maximum peak value and the second largest peak value in the amplitude spectrum of vowels. The hearing aid according to any one of claims 1 to 8, wherein the high frequency band in which both waves are rectified is in a band of 2 kHz or more. The hearing aid according to any one of claims 1 to 8, wherein the high frequency band in which both waves are rectified is in a band of 1.5 kHz or more. The hearing aid according to any one of claims 1 to 8, wherein the high frequency band in which both waves are rectified is in a band of 1 kHz or more. The hearing aid according to any one of claims 1 to 11, wherein the high frequency band in which both waves are rectified is in a band of 8 kHz or less. The hearing aid according to any one of claims 1 to 11, wherein the high frequency band in which both waves are rectified is in a band of 4 kHz or less.

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